2-(omega-hydroquinonyl-alkyl)-anthraquinones

ABSTRACT

This application relates to the synthesis of compounds having the formula:   WHEREIN EACH X is hydroxy or amino (including secondary amino, e.g., alkylamino), and R is an alkylene radical, preferably a lower alkylene radical containing 1-6 carbon atoms; and to compounds having the formula: WHEREIN R is the same as above; as well as to the use of such compounds in photographic developer compositions and developing processes. The compounds of formula (A) are also suitable for use as dyes for textile fibers.

United States Patent Solodar [54] Z-(OMEGA-HYDROQUINONYL- ALKYL)-ANTHRAQUINONES [72] Inventor: Warren E. Solodar, Newton Centre,

Mass.

[73] Assignee: Polaroid Corporation,

bridge, Mass.

[22] Filed: Nov. 1, 1967 [211 App]. No.: 703,197

Related US. Application Data [62] Division of Ser. No. 370,345, May 26, 1964,

abandoned.

Cam-

[52] US. Cl. ..260/380, 8/39, 8/40, 96/29 D, 96/55, 96/66 R, 260/383, 260/521 R, 260/590, 260/613 R, 260/619 A, 260/619 [51] Int. Cl ..C07c 49/74 [58] Field of Search ..260/380, 383; 96/29 D, 66, 96/55 [56] References Cited FOREIGN PATENTS OR APPLICATIONS 626,959 9/1961 Canada ..260/380 OTHER PUBLICATIONS Lubs, Dyes and Pigments, 1955, pp. 338, 362.

[ 51 Sept. 12,1972

Primary Examiner-Lorraine A. Weinberger Assistant Examiner-Robert Gerstl Attorney-Brown and Mikulka, Stanley H. Mervis and Alvin lsaacs [5 7] ABSTRACT This application relates to the synthesis of compounds having the formula:

on on A Q FW K H V X OH 011 wherein each X is hydroxy or amino (including secondary amino, e.g., alkylamino), and R is an alkylene radical, preferably a lower alkylene radical containing l-6 carbon atoms; and to compounds having the forof such compounds in photographic developer compositions and developing processes.

The compounds of formula (A) are also suitable for use as dyes for textile fibers.

4 Claims, No Drawings emulsions, in which the novel developing agent is capable of developing an exposed silver halide emulsion and imparting a reversed or positive colored image of the developed image to a superposed image-receiving material.

A further object is to provide novel silver halide developing agents and novel products, processes and compositions suitable for use in preparing monochromatic and multichromatic photographic images.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the processes involving the several steps and the relation and order of one or more of such steps with respect to each of the others, and the products and compositions possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

Certain of the objects of this invention may be accomplished by the use of novel dyes which have the ability to develop images present in an exposed silver halide emulsion; thus they may be referred to as dye developers. These novel dyes or dye developers will be further described hereinafter.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description.

The photographic processes and compositions disclosed herein are particularly useful in the treatment of an exposed silver halide emulsion, whereby a positive dye image may be imparted to another element, herein referred to as an image-carrying or image-receiving element.

US. Pat. No. 2,983,606, issued May 9, 1961 to Howard G. Rogers, discloses diffusion transfer processes wherein a photographic negative material, such as a photographic element comprising an exposed silver halide emulsion, is developed in the presence of a dye developer to impart to an image-receiving layer a reversed or positive dye image of the developed image by permeating into said emulsion a suitable liquid processing composition and bringing said emulsion into superposed relationship with an appropriate imagereceiving layer. The inventive concepts herein set forth provide novel dye developers for use in such processes.

In carrying out the process of this invention, a photosensitive element containing a silver halide emulsion is exposed and wetted with a liquid processing composition, for example by immersing, coating, spraying, flowing, etc., in the dark, and the photosensitive distribution superposed prior to, during or after wetting, on an image-receiving element. In a preferred embodiment, the photosensitive element contains a layer of dye developer, and the liquid processing composition is applied to the photosensitive element in a uniform layer as the photosensitive element is brought into superposed position with an image-receiving element. The liquid processing composition permeates the emulsion to provide a solution of dye developer substantially uniformly distributed therein. As the exposed silver halide emulsion is developed, the oxidation product of the dye developer is immobilized or precipitated in situ with the developed silver, thereby providing an imagewise distribution of unoxidized dye developer dissolved in the liquid processing composition. This immobilization is apparently due, at least in part, to a change in the solubility characteristics of the dye developer upon oxidation, and especially as regards its solubility in alkaline solutions. It may also be due, in part, to a tanning effect on the emulsion by the oxidized developing agent. At least part of this imagewise distribution of unoxidized dye developer is transferred, by imbibition, to a superposed imagereceiving layer. The image-receiving layer receives a depthwise diffusion, from the emulsion, of unoxidized dye developer, without appreciably disturbing the imagewise distribution thereof, to provide a reversed or positive, colored image of the developed or negative image. The image-receiving element may contain agents adapted to mordant or otherwise fix the dif fused, unoxidized dye developer. lmbibition periods of approximately one minute have been found to give good results, but this contact period may be adjusted where necessary to compensate for variations in temperature or other conditions. The desired positive image is revealed by stripping the image-receiving layer from the silver halide emulsion at the end of the imbibition period.

The dye developers of this invention may be utilized in the photosensitive element, for example in, on or behind the silver halide emulsion, or they may be utilized in the image-receiving element or in the liquid processing composition. In a preferred embodiment, a coating or layer of the dye developer is placed behind the silver halide emulsion, i.e., on the side of the emulsion adapted to be located most distant from the photographed subject when the emulsion is exposed and preferably also adapted to be most distant from the image-receiving layer when in superposed relationship therewith. Placing the dye developer behind the emulsion layer, as in the preferred embodiment, has the advantage of providing increased contrast in the positive image, and also minimizes any light-filtering action by the colored dye developer. In this preferred embodiment, the layer of dye developer maybe applied by using a coating solution containing about 0.5 to 8%, by weight, of the dye developer. Similar concentrations may be used if the dye developer is utilized as a component of the liquid processing composition In an especially useful mode of disposing the dye developers in the photosensitive elements, the dye developer is dissolved in a water-immiscible solvent and then dispersed in a gelatin coating solution.

The liquid processing composition which is used in the processes herein disclosed comprises at least an aqueous solution of an alkaline compound, for exam- 1s to be applied to the emulsion by being spread 5 thereon, preferably in a relatively thin, uniform layer, it may also include a viscosity-increasing compound constituting film-forming material of the type which, when spread over a water-absorbent base, will form a relatively firm and relatively stable film. A preferred film forming material is a high molecular weight polymer such as a polymeric, water-soluble ether inert to an alkali solution, as, for example, a hydroxyethyl cellulose or sodium carboxymethyl cellulose. Other film-forming materials or thickening agents whose ability to increase viscosity is substantially unaffected when left in solution for a long period of time may also be used.

The novel dye developers of this invention are anthraquinone dyes having the formula:

(A) X OH AAA w i H l X 0 on i it wherein each X is hydroxy or amino (including secondary amino, e.g., alkylamino), and R is an alkylene radical, preferably a lower alkylene radical containing one to six carbon atoms, such as CH CH CH2-,-CH -CH CH ,CHCH2-CH2 l CH As examples of dye developers within the scope of Formula (A), mention may be made of the following:

(4) NH; ()ll ()ll NH: ()II ()ll (5) Oil Oil 1 NH: 0 on I on O I ll (7) C 2H5 0 Ha CaHs O OH

It will be noted that the compounds of Formula (A),

e.g., compounds 1-10, are new dye developers having a single developer moiety linked to the anthraquinone dye nucleus in the 2-position by an alkylene group.

The dye developers of this invention may be OCH,

CO JJCHa with a bis-hydroquinonyl compound of the formula:

on on E Tat J ()H on to form a dye developer of Formula (A) wherein each X is hydroxy, which dye developer may be represented by the following formula:

wherein X is a primary or secondary amino group.

The bis-hydroquinonyl compounds of Formula (B), which are also useful as silver halide developing agents in black-and-white photographic processes, may be prepared by reacting with hydroquinone a compound of the formula:

wherein n is a positive integer of at least 1, to provide the requisite number of carbon atoms in the alkylene group of the dye developer, e.g., a positive integer from one to seven, the reaction being performed in the presence of a suitable catalyst such as boron trifluoride,

to form a compound of the formula:

which is then hydrogenated in the presence of a suitable hydrogenation catalyst such as palladium/carbon to form the desired bis-hydroquinonyl compound of F ormula (B),

As examples of useful compounds within the scope of Formula (E), mention may be made of gentisic acid, homogentisic acid, p-dihydroxyhydro-cinnamic acid, a-methyl-2,S-dihydroxyhydrocinnamic acid, a-ethyl- 2,5-dihydroxyhydrocinnamic acid, etc.

Certain of the compounds of Formula (B) may also be formed, as noted by Example l), by reacting 2,5- dimethoxy-benzaldehyde or its homologues with a suitable ketone such as acetone to form the corresponding alpha, omegabis-dimethoxyphenyl-di-unsaturated ketone, which is then reduced and the methoxy groups hydrolyzed to form the desired compound of Formula (B).

This latter synthesis, as applied to the synthesis of l,5-bis-hydroq'uinonyl-pentane, may be illustrated by the following equations:

A) C Ha OCH; lCHs (I)CHJ l l OCH: OCH:

O OH; OCH:

| 0 CH3 OCH;

OCH: OCH;

The following examples show by way of illustration and not by way of limitation the preparation of the novel compounds of this invention.

EXAMPLE 1 A mixture of 163.0 gm. of 2,5-dimethoxybenzaldehyde, 28.4 gm. of acetone and 294.0 ml. of ethanol 3A was added portionwise over a period of ten minutes to a well-stirred solution of 98.0 ml. of 50 percent sodium hydroxide in water, 882.0 ml. of water and 785.0 ml. of ethanol 3A. The temperature was maintained in a range of l9-22 C. during the entire reaction. The above mixture was stirred for 1 hour. [A precipitate began forming approximately one-half hour after admixture] The reaction mixture was then allowed to stand for one-half hour without stirring, after which it was filtered to obtain a yellow precipitate. This precipitate was desiccated over KOl-l P in vacuo for two days, after which it was recrystallized in 1500.0 ml. of a 50/50 benzene-hexane solution. 127.0 gm. (73 percent yield) of yellow needle crystals were recovered by concentrating the solvent at room temperature. This compound, l,5-bis-(2,5-dimethoxybenzal)-acetone, m.p. l05106 C., had the following structural formula:

C a OCHa I OCHs (I)CH3 l 1.87 gm. of this compound were dissolved in 100 ml. of hot ethanol 3A. 2.0 gm. of percent Pd/BaSO. were then added and the resulting mixture was hydrogenated on a Parr shaker for 23 minutes. After uptake of two equivalents of hydrogen, a white product precipitated. 50.0 ml. of ethanol 3A were added and the mixture was heated until solution was complete, after which the Pd/BaSO catalyst was filtered off. The solution was allowed to concentrate at room temperature in a hood to obtain white flakes, m.p. 72.5-74 C. Desiccation overnight over P 0 in vacuo yielded 9.73

gm. percent yield) of l,5-bis-(2',5'-dimethoxybenzyl)-acetone of the formula:

12.75 gm. of the latter compound were added to a mixture of zinc amalgam [prepared by admixing 60.0 gm. mossy zinc and 6.0 gm. HgCL adding 6.0 ml. of concentrated HCl and 160 ml. of water; shaking at room temperature for 5 minutes; and then decanting, the zinc amalgam being covered immediately after preparation with 40.0 ml. of water, 60.0 ml. of acetic acid and 80.0 ml. of concentrated HCl The resulting mixture was refluxed overnight and then allowed to cool. After cooling, the mixture was extracted several times with ether. The ether extracts were washed free of acid with a carbonate solution. The ether was dried over MgSO filtered and evaporated. The residual oil crystallized on seeding. Crystallization from 35.0 ml. of isopropyl alcohol gave 11.3 gm. of l,5-bis-(2',5-dimethoxyphenyl)-pentane, a white solid, mp. 4647.5 C., having no carbonyl band in the l.R., and having the following formula:

7.13 gm. of this compound, 75.0 ml. of 48% HBr, 5.0 ml. of concentrated HCl and 120.0 ml. of glacial acetic acid were placed in a 250 ml. RB flask, fitted with an adequate condenser, wrapped in aluminum foil and refluxed for five hours. During the last hour the condenser was fitted for downward distillation. Approximately ml. of clear liquid came over at 100-l 15 C. After the liquid remaining in the reaction flask was cooled (some precipitating occurred), ml. of ether and 150 ml. of water were added. The ether layer was collected and the water extracted two more times with 50.0 ml. portions of ether. The combined ether layers were treated with charcoal until no further color change was noticed. The ether was then dried by the addition of anhydrous MgSO and filtered. The evaporation of the ether on a steam bath left a solid, tan-colored residue which was washed with 75 .0 ml. of hexane, filtered and air-dried to yield 5.15 gm. (86 percent yield) of l,5-bis-hydroquinonyl-pentane, a light tan powder, m.p. 167l 68.5 C., of the formula:

EXAMPLE 2 To a melt of 80.0 gm. of anhydrous aluminum chloride and 30.0 gm. of sodium chloride at 190 C. was gradually added in 30 minutes with thorough stirring, an intimate mixture of 5.9 gm. of 1,5-bishydroquinonyl-pentane (as prepared in Example 1) and 4.0 gm. of 3,6-dimethoxyphthalic anhydride. The resulting mixture was heated to 220 C. and stirring was continued for 45 minutes. The mixture was then cooled to provide a solidified blue mass which was pulverized in a mortar, then cautiously added in portions to 250.0 ml. of warm water containing 15.0 ml. of concentrated HCl This formed a purple precipitate which was filtered off, washed with hot water, and desiccated in vacuo over P 7 gm. (81 percent yield) of a crude product, m.p. l95205 C., was obtained. Two crystallizations from acetic acid yielded 2-(omega-hydroquinonyl-pentyl)-l ,4,5 ,S-tetrahydroxyanthraq uinone, a purplish powder, m.p. 153-l55 G, A at 560 m l; e== 18,400, having the following structural formula:

on (H) OH ()11 fionronrcm-onronr K/ I \l/ 011 0 on 0H Analysis Calculated for C H- O C 66.6 H 4.9 Found: C=6.70 H=4.9

EXAMPLE 3 To a deaerated solution of 11.8 gm. of 2-(omegahydroquinonyl-pentyl 1 ,4 ,5 ,8-tetrahydroxyanthraquinone (as prepared in Example 2) in 120.0 ml. of 2N KOl-l were added 5.8 gm. of freshly prepared zinc amalgam (prepared as in Example 1). The resulting mixture was stirred and refluxed under nitrogen for 7 hours, adding a fresh charge of zinc amalgam after the fourth hour. The reaction, after standing at room temperature overnight under nitrogen, was continued for 2 hours longer the following morning, adding a third charge of zinc amalgam. Progress of the reaction was followed spectrally, observing the build-up of leuco bands at 456 and 484 mu. The reaction was continued to the disappearance of the peaks at 546 and 560 mph The mixture was then allowed to cool, after which it was acidified to pH 5 by the gradual addition of a deaerated mixture of 40 ml. of acetic acid and 70.0 ml. of water. The brown precipitate that separated was filtered off and desiccated to yield 10.8 gm. (91 percent) of the leuco form of the tetrahydroxyanthraquinone starting material, a light brown solid, mp. l25-135 C. A deaerated mixture of 9.04 gm. of this leuco compound, 4.35 gm. of 3-aminopentane and 35.0 ml. of dimethylformamide was stirred and heated on the steam bath under nitrogen for 1 hour. 11.4 gm. of pyridine N-oxide were added and the heating and stirring continued under nitrogen for seven hours longer, following spectrally the build-up of the 625 and 679 peaks, and the disappearance of the leuco bands. A fresh charge of pyridine N-oxide was added and the oxidation continued an additional 18 hours. The mixture was acidified with 5.0 ml. of acetic acid and poured into 500.0 ml. of dilute HCl. The precipitate that separated was filtered off and desiccated in vacuo over P 05, yielding 9.4 gm. of a blue solid. This solid was purified by extraction with 250 ml. of benzene under nitrogen for three hours. Evaporation of the benzene in vacuo gave 2-(omega-hydroquinonyl-pentyl)-l,4- dihydroxy-S,8-bis-a-ethyl-propylamino-anthraquinone, a shiny blue solid, X at 681 and 626 my. in methyl cellosolve; e 32,600 and e 21,400, and having the following structural formula:

sink

N O OH I 011 wo 112-0 Hz-CHz-CIIz-CIL l on 0211, 02115 EXAMPLE 4 Substitution of 2-amino-butane for 3-aminopentane in the process of Example 3 yielded a blue solid, 2- (omega-hydroquinonyl-pentyl)-1 ,4-dihydroxy-5 ,8-bisa-methyl-propylamino-anthraquinone, having the same A as the dye developer prepared in Example 3, and having the following formula:

H OH

O OH

CzHs CH2 1n Examples 2, 3 and 4, analysis of the proton magnetic resonance spectra indicated that the amino substituent was substituted in the 5,8-positions, as shown by the structural formulae, rather than in the 1,4-positions.

The following examples illustrate the use of the novel bis-hydroquinonyl developing agents of this invention in the preparation of black-and-white images.

EXAMPLE 5 Water 100.00 cc.

KOH 11.20 g. Hydroxyethyl cellulose (high viscosity) [Commercially available from Hercules Powder Co., under the trade name of Natrasol 250] 3.90 g. Benzotriazole 3.50 g. Sodium thiosulfate 0.50 g. N-benzyl-oz-picolinium bromide 2.00 g. Zinc nitrate 0.50 g. Lithium nitrate 0.50 g.

to provide a negative image having a D of 0.50 and a D,,,,,, of 0.02 for a A of 0.48. Upon careful inspection of the negative image, the bis-hydroquinonyl developer was observed to be a good discriminating, low staining, black-and-white developer.

EXAMPLE 6 A silver iodobromide emulsion was exposed and then developed by spreading between the thus-exposed emulsion and a superposed silver-receptive stratum at a gap of .0022 in. an aqueous processing composition comprising:

Water 8289 cc. Hydroxyethyl cellulose 366 gm. Sodium sulfite 260 gm. Sodium thiosulfate (hypo) 741 gm. Potassium iodide 15 gm. 6-nitrobenzimidazole l0.8 gm. gm. Sodium hydroxide 425 gm.

After an irnbibition period of ten seconds, the silverreceptive stratum was separated to reveal a clear positive silver image.

. The following examples illustrate the use of novel dye developers of this invention in the preparation of color images.

EXAMPLE 7 A photosensitive element was prepared by coating a gelatin subcoated film base at a speed of 10 feet/minute with a solution comprising 0.33 gm. of 2-(omegahydroquinonyl-pentyl)-l ,4-dihydroxy-S ,8-bis-amethyl-propylamino-anthraquinone (prepared as in Example 4) and 16 drops of dirnethylforrnamide dissolved in 10.0 cc. of 2 percent cellulose acetate hydrogen phthalate in methyl cellosolve. After this coating dried, a red-sensitive silver iodobromide emulsion was coated on at a speed of 5 feet/minute and allowed to dry. This photosensitive element was exposed for 2 seconds and processed by spreading between the thus-exposed photosensitive element and a superposed image-receiving element, at a gap of 0.0026 inch, the aqueous processing composition of Example 5. The image-receiving element was prepared in accordance with the disclosure of the copending application of Edwin H. Land, Ser. No. 234,864, filed Nov. 1, 1962, and comprised a layer of a 2:1 mixture, by weight, of polyvinyl alcohol and poly-4-vinylpyridine, a layer of polyvinyl alcohol, and a layer of a half-butyl ester of poly-(ethylene/maleic anhydride) coated on a baryta paper support. After an imbibition period of approximately one minute, the image-receiving element was separated and contained a cyan image.

EXAMPLE 8 A photosensitive element was prepared by coating a gelatin subcoated film base at a speed of 10 feet/minute with a solution comprising 0.18 gm. of 2-(omegahydroquinonyl-pentyl 1 ,4,5 ,8-tetrahydroxyanthraquinone (as prepared in Example 2) and ten drops of dimethylformamide dissolved in 5.0 cc. of a solution of 2 percent cellulose acetate hydrogen phthalate in a 50/50 acetone-tetrahydrofuran mixture. After this coating dried, a green-sensitive silver iodobromide emulsion was coated on at a speed of 5 feet/minute and allowed to dry. This photosensitive element was exposed for 2 seconds and processed in the manner described in the preceding example to provide a reddish transfer image.

The addition of 0.2 gm. of 4'-methylphenylhydroquinone to the processing solution gave a comparable image having an appreciably lower D,,,,,,

While, for purposes of illustrating the invention, the bis-hydroquinonyl developing agent (Example 5) and the dye developer (Examples 7-8) have been shown to be initially in a layer in the photosensitive element, it will be appreciated that the invention is not so limited and they may, for example, be present initially in the processing composition.

As was mentioned heretofore, the bis-hydroquinonyl silver halide developing agents of this invention are good discriminating developers which give little or no stain, making them useful both in black-and-white photography and as auxiliary or accelerating developers in color photographic processes such as those employing dye developers.

The dye developers of this invention are useful single-ended anthraquinone dye developers, i.e., anthraquinone dyes containing a single developing group linked to the dye nucleus. Particularly useful are the cyan dye developers obtained where X of the formula is a secondary amino group. The present invention thus provides an eflective method for providing single-ended developers, particularly cyan dye developers, useful in preparing color images.

The dye developers of this invention are also useful in integral multilayer photosensitive elements for use in multicolor diffusion transfer processes. As an example of such photosensitive elements, mention may be made of the photosensitive elements disclosed and claimed in the copending U.S. application of Edwin H.'Land and Howard G. Rogers, Ser. No. 565,135, filed Feb. 13, 1956, wherein at least two selectively sensitized photosensitive strata are superposed on a single support and are processed, simultaneously and without separation, with a single common irnage-receiving element. A suitable arrangement of this type comprises a support carrying a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum and a blue-sensitive silver halide emulsion stratum, said emulsions having associated therewith, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer. In one of the preferred embodiments of photosensitive elements of this type, the dye developers are disposed in separate alkali-permeable layers behind the photosensitive silver halide emulsion stratum with which they are associated.

The photosensitive elements within the scope of this invention may be used in film units which contain a plurality of photosensitive frames. The photosensitive elements of this invention are especially useful in composite roll film and film pack structures intended for use in a Polaroid Land Camera, sold by Polaroid Corporation, Cambridge 39, Mass., or a similar camera structure such, for example, as the roll film type camera forming the subject matter of U.S. Pat. No. 2,435,717, issued to Edwin H. Land on Feb. 10, 1948, or the film pack type camera shown in US. Pat. No. 2,991,702, issued to Vaito K. Eloranta on July 11, 1961. In general, such composite roll films comprise a photosensitive roll, a roll of image-receiving material and a plurality of pods containing an aqueous alkaline processing solution. The rolls and pods are so associated with each other that, upon processing, the photosensitive element may be superposed on the image-receiving element and the pods may be ruptured to spread the aqueous alkaline processing solution between the superposed elements. The nature and construction of the pods used in such units are well known to the art. See, for example, US. Pat. Nos. 2,543,181 and 2,634,886, issued to Edwin H. Land.

It will be noted that the liquid processing composition may contain one or more auxiliary or accelerating silver halide developing agents, such as pmethylaminophenol (Metol); 2,4-diaminophenol (Amidol); benzylaminophenol; hydroquinones; a substituted hydroquinone such as toluhydroquinone, phenylhydroquinone, or 4-methylphenylhydroquinone; or a 3-pyrazolidone such as l-phenyl-3-pyrazolidone. These silver halide developing agents are substantially colorless, at least in their unoxidized form. It is possible that some of the dye developer oxidized in exposed areas may be oxidized by an energy transfer reaction with oxidized auxiliary developing agent.

In addition, development may be effected in the presence of an onium compound, particularly a quaternary ammonium compound, in accordance with the processes disclosed and claimed in the copending application of Milton Green and Howard G. Rogers, Ser. No. 50,851, filed Aug. 22, 1960.

The dye developers of this invention may be used also in conventional photographic processes, such as tray or tank development of conventional photosensitive films, plates or papers to obtain black-and-white, monochromatic or toned prints or negatives. By way of example, a developer composition suitable for such use may comprise an aqueous solution of approximately 1-2 percent of the dye developer, 1 percent sodium hydroxide, 2 percent sodium sulfite and 0.05 percent potassium bromide. After development is completed, any unreacted dye developer is washed out of the photosensitive element, preferably with an alkaline washing medium or other medium in which the unreacted dye developer is soluble. The expression toned is used to designate photographic images wherein the silver is retained with the precipitated dye, whereas monochromatic is intended to designate dye images free of silver.

It should be noted that the dye developers of this medium are self-sufficient to provide the desired color image and do not depend upon coupling reactions to produce the desired color. They thus provide a complete departure from conventional photographic color processes in which the color is produced by a coupling reaction between a color former or coupler" and the oxidized developing agent, as well as so-called auto-coupling processes in which color is obtained by a reaction of the oxidized developing agent with unoxidized developing agent.

It will be apparent that, by appropriate selection of the image-receiving element from among suitable known opaque and transparent materials, it is possible to obtain either a colored positive reflection print or a colored positive transparency. Likewise, the inventive concepts herein set forth are adaptable for multicolor work by the use of special photographic materials, for example, film materials of the type containing two or more photosensitized elements associated with an appropriate number of image-receiving elements and adapted to be treated with one or more liquid processing compositions, appropriate dye developers suitable to impart the desired subtractive colors being incorporated in the photosensitized elements or in the liquid processing compositions. Examples of such photographic materials are disclosed in US. Pat. No. 2,647,049 to Edwin H. Land.

As examples of useful image-receiving materials, mention may be made of nylon, e.g., N-methoxymethyl-polyhexamethylene adipamide, polyvinyl alcohol, and gelatin, particularly polyvinyl alcohol or gelatin containing a dye mordant such as po1y-4-vinylpyridine. The image-receiving element also may contain a development restrainer, e.g., l-phenyl-S-mercaptotetrazole, as disclosed in the copending application of Howard G. Rogers and Harriet W. Lutes, Ser. No. 50,849, filed Aug. 22, 1960.

The dye developers herein set forth are also useful in the formation of colored images in accordance with the photographic products and processes described and claimed in US. Pat. No. 2,968,554, issued to Edwin H. Land on Jan. 17, 1961.

The novel dye developers herein disclosed are also suitable for use as dyes for textile fibers, such as nylon.

In the preceding portions of the specification, the expression color has been frequently used. This expression is intended to include the use of a plurality of colors to obtain black.

Since certain changes may be made in the above products, compositions and processes without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

l. A compound of the formula:

wherein each X is a member of the group consisting of hydroxy and amino radicals; and R is an alkylene radical having from one to six carbon atoms. 

2.
 3. 